Submitted form values not updated in model when adding <f:ajax> to <h:commandButton>

I'm learning how to use ajax within jsf, I made a page that does actually nothing, an input text that is filled with a number, submitted to the server, call the setter for that element with the value submitted, and display the getter's value.

As you see, this is a request scoped bean, whenever I click the button the server shows that it creates an instance of the bean, but the setter method is never called, thus, the getter return always "1" as the value of the string.